Platinum compounds comprise one of the most widely used and successful groups of cytotoxic drugs worldwide, given their efficacy in a wide spectrum of tumor types. Each year more than 5.8 million patients are diagnosed with cancers of colon, rectum, cervix, endometrium, bladder, stomach, head and neck, lung, esophagus, pancreas, osteosarcoma, ovary, and testis, for which first-line therapy can potentially include platinating agents. Platinum now also shows promise for triple-negative breast cancer. Despite over 30 years of clinical use, however, there are no means to identify patients at risk for platinum toxicity who might be offered alternative therapies, or reduced-dose regimens. For patients whose management must include platinating agents, there are no preventive measures and no treatment for these debilitating toxicities. Long-term ototoxicity affects 19-77% of patients, with 35-65% developing tinnitus. Long-term sensory neuropathies affect 30-40% patients. The underlying mechanisms of long-term cisplatin toxicity remain largely un- known. GWAS now provides translational tools to begin to characterize the underlying mechanisms associated with these serious toxicities, with a goal of eventually developing preventive and interventional strategies. The objective of this proposal is to evaluate genetic susceptibility to long-term platinum toxicity among a well- characterized clinical cohort of 3,838 testicular cancer survivors (TCS). This population was selected as the optimal group in which to study the genetic underpinnings of platinum toxicity because of their young age at diagnosis, homogeneity of cisplatin-based therapy, high cure rate, and lifelong risk of treatment sequelae. Moreover, the regimens that we study remain the standard of care. We along with experts in the field recently published a JNCI Commentary (2010;102:1-17), which set forth a new platinum-based research strategy, with an emphasis on providing for the first time a comprehensive understanding of genetic susceptibility to long-term toxicity. Our proposal derives from these recommendations. For almost 2 years, study co-investigators (expert oncologists who daily treat and follow TCS) have systematically queried patients, confirming that their populations are highly motivated to participate in the current study. Our major goals are: 1. For the first time, and through a multi-institutional effort, to establish a large clinically well-characterized cohort of platinum-treated TCS available for lifelong follow-up to enable study of the genetic underpinnings of long-term toxicities; 2. To identify SNPs associated with long-term cisplatin ototoxicity and neurotoxicity; and 3. To determine and validate the extent to which candidate SNPs identified through studies of cellular susceptibility to cisplatin are associated with clinical long-term ototoxicity and neurotoxicity. The novelty of our study is that it comprehensively evaluates for the first time genetic susceptibility to long-term cisplatin toxicity in patients known to be at substantial lifelong risk and will include functional studies. Results from our translational research will potentially impact the millions of patients who are diagnosed annually worldwide with cancers for which therapy can include platinum, not limited to TCS. Our results will eventually permit identification of patients at high risk for long-term toxicity, and the development of preventive and interventional strategies. 1